Systems and methods for anatomical alignment

ABSTRACT

Systems and methods for anatomical alignment are disclosed herein. In some embodiments, the systems and methods can provide accurate and continuous intraoperative validation of anatomical alignment, e.g., of the spine, hips, pelvis, and/or shoulders. An exemplary system can include a sensor and marker arrangement for measuring coronal imbalance. Another exemplary system can include a sensor and marker arrangement for shoulder or pelvic leveling. Yet another exemplary system can include a mechanical frame for establishing a simulated ground plane and projecting a plumb line from the simulated ground plane.

FIELD

Systems and methods for anatomical alignment are disclosed herein.

BACKGROUND

Anatomical misalignment is a condition affecting many patients and forwhich surgical intervention is often required. The misalignment canoccur naturally due to age, degenerative conditions, deformities, and soforth. The misalignment can also be caused or exacerbated by a surgicalprocedure. For example, in spinal surgery, the insertion of a prosthesisor adjustment or removal of bone can result in misalignment of the spineor other anatomical parts of the patient. In some instances, a surgicalprocedure to correct sagittal balance of the spine can inadvertentlycause increased spinal curvature in the coronal plane. In other cases,the shoulders, hips, or pelvis can become unequal, with one side beinghigher than the other. Misalignment of the spine, hips, pelvis, orshoulders can have serious adverse complications such as poor patientaesthetic index (AI) score, increased wear and tear on patient joints,severe pain, uneven gait, osteoarthritis, and difficulty in performingfunctions of daily living. Surgical revision is often needed to correctthe misalignment.

Anatomical alignment can be difficult to assess and measure during thesurgery, though it can be important to do so as this is often the onlytime that a misalignment can be corrected. Existing techniques forassessing anatomical alignment during surgery typically include use ofmany cobbled together methods such as “eyeballing,” experience,estimation, or use of a manual T-square type device. Current mechanicalsolutions for estimating alignment tend to be bulky,visually-obstructive to the surgery, cumbersome to use, inaccurate, andusable only with surgical intervention. In addition, such devices do notprovide for continuous intraoperative validation. Rather, the surgeonmust use their discretion as to when to assess the alignment, which isusually only at a few discrete points during the procedure.

Accordingly, there is a need for improved systems and methods foranatomical alignment.

SUMMARY

Systems and methods for anatomical alignment are disclosed herein. Insome embodiments, the systems and methods can provide accurate andcontinuous intraoperative validation of anatomical alignment, e.g., ofthe spine, hips, pelvis, and/or shoulders. An exemplary system caninclude a sensor and marker arrangement for measuring coronal imbalance.Another exemplary system can include a sensor and marker arrangement forshoulder or pelvic leveling. Yet another exemplary system can include amechanical frame for establishing a simulated ground plane andprojecting a plumb line from the simulated ground plane.

In some embodiments, a method for assessing anatomical alignmentincludes attaching a pointing device to a first location on a patient;attaching a marker to a second location on a patient; and projecting avisual indicator from the pointing device onto a measurement scale ofthe marker to provide a direct visual indication of an anatomicalmeasurement of the patient.

The first location can be a sacral vertebra and the second location canbe a thoracic or cervical vertebra. The anatomical measurement can be aCVA of the patient. Attaching the pointing device can include aligningthe visual indicator such that it is parallel to a CSVL of the patient.Attaching the marker can include aligning a measurement axis of themeasurement scale such that it is perpendicular to the CSVL of thepatient. Attaching the marker can include aligning a measurement axis ofthe measurement scale such that it is perpendicular to a vertical plumbline extending from the first location.

In some embodiments, a system for assessing anatomical alignmentincludes a pointing device having an attachment element for attachingthe pointing device to a first anatomy of a patient; and a marker havingan attachment element for attaching the marker to a second anatomy ofthe patient, the marker having a measurement scale extending along ameasurement axis; wherein the pointing device projects a visualindicator onto the measurement scale, thereby providing a visualindication of an offset between the first anatomy and the second anatomyalong the measurement axis.

The pointing device can include a laser pointer. The attachment elementof the pointing device can include at least one of a bone pin and a boneanchor. The system can include an alignment guide for aligning at leastone of the pointing device and the marker with respect to the patient.The alignment guide can include at least one of a bubble level, anaccelerometer, gyroscope, or other sensor, and a beacon or marker foruse with a surgical navigation system.

In some embodiments, a method for assessing anatomical alignmentincludes attaching a first range finder component at a first location ona patient; positioning a second range finder component at a referenceaxis; attaching a third range finder component at a second location onthe patient; positioning a fourth range finder component at thereference axis; measuring a first time of flight between the first andsecond components; measuring a second time of flight between the thirdand fourth components; and comparing the first and second times offlight to determine an anatomical measurement of the patient.

The first location can be an inferior vertebra of the patient and thesecond location can be a superior vertebra of the patient. Theanatomical measurement can be a CVA of the patient. The method caninclude communicating the determined anatomical measurement to a userusing at least one of a visual indicator, an audible indicator, atactile indicator, and an electronic display. The first and secondcomponents can be aligned along a first axis that is perpendicular to aCSVL of the patient and the third and fourth components can be alignedalong a second axis that is perpendicular to the CSVL of the patient.

In some embodiments, a system for assessing anatomical alignmentincludes a first range finder including first and second components, thefirst component having an attachment element for attaching the firstcomponent to a first anatomy of a patient, the first range finderconfigured to measure a first distance between the first and secondcomponents; a second range finder including third and fourth components,the third component having an attachment element for attaching the thirdcomponent to a second anatomy of the patient, the second range finderconfigured to measure a second distance between the third and fourthcomponents; and a controller configured to compare the first and seconddistances and to display a difference between the first and seconddistances on an electronic display.

Each attachment element can include at least one of a bone pin and abone anchor. The system can include an alignment guide for aligning atleast one of the first, second, third, and fourth components withrespect to the patient.

In some embodiments, a method for assessing anatomical alignmentincludes attaching a pointing device at a first location of a patient;attaching a first range finder component at a second location of thepatient, the second location being aligned in the coronal plane of thepatient with the first location; attaching a second range findercomponent at a third location of the patient; and measuring a time offlight between first and second range finder components to determine ananatomical measurement of the patient.

The first location can be a sacral vertebra and the third location canbe a thoracic or cervical vertebra. The anatomical measurement can be aCVA of the patient. Attaching the pointing device can include aligning avisual indicator emitted by the pointing device such that it is parallelto the CSVL of the patient, the visual indicator being incident upon thefirst range finder component. Attaching the first and second rangefinder components can include positioning the first and secondcomponents along an axis that is perpendicular to the CSVL of thepatient.

In some embodiments, a system for assessing anatomical alignmentincludes a pointing device having an attachment element for attachingthe pointing device to a first anatomy of a patient; a range finderincluding first and second components, the first component having anattachment element for attaching the first component to a second anatomyof the patient, the second component having an attachment element forattaching the second component to a third anatomy of the patient; therange finder configured to measure a distance between the first andsecond components; and a controller configured to display the measureddistance between the first and second components on an electronicdisplay.

In some embodiments, a method for assessing anatomical alignmentincludes attaching an imaging device at a first location of a patient;attaching a marker at a second location of the patient, the marker beingwithin a field of view of the imaging device; calibrating the field ofview of the imaging device to a reference axis of the patient; anddetermining from one or more images captured by the imaging device anoffset between the marker and the reference axis as an anatomicalmeasurement of the patient.

The first location can be an inferior vertebra and the second locationcan be a superior vertebra. The anatomical measurement can be a CVA ofthe patient. The method can include displaying the offset on anelectronic display.

In some embodiments, a system for assessing anatomical alignmentincludes an imaging device configured to capture images of a field ofview of the imaging device, the field of view being calibrated to areference axis of a patient, the imaging device having an attachmentelement for attaching the imaging device to a first anatomy of thepatient; a marker that, when disposed within the field of view of theimaging device, is identifiable in images captured by the imagingdevice, the marker having an attachment element for attaching the markerto a second anatomy of the patient; and a controller configured todetermine from one or more images captured by the imaging device anoffset between the marker and the reference axis as an anatomicalmeasurement of the patient, the controller being further configured todisplay the anatomical measurement on an electronic display.

In some embodiments, a method for assessing anatomical alignmentincludes attaching a first range finder component at a first location ona patient; attaching a second range finder component at a left anatomyof the patient; attaching a third range finder component at a rightanatomy of the patient; measuring a first time of flight between thefirst and second components; measuring a second time of flight betweenthe first and third components; and comparing the first and second timesof flight to determine an anatomical alignment of the left and leftanatomies of the patient.

The left and right anatomies can be the patient's left and rightshoulders and the anatomical alignment can include a shoulder balance ofthe patient. The left and right anatomies can be the patient's left andright hips and the anatomical alignment can include a hip balance of thepatient. The first component can include a left transceiver aimedtowards the second component and a right transceiver aimed towards thethird component. The method can include displaying first and seconddistances represented by the first and second times of flight on anelectronic display. The first location can include a vertebra of thepatient.

In some embodiments, a method for assessing anatomical alignmentincludes attaching an imaging device at a first location on a patient;positioning a first marker at a left anatomy of the patient; positioninga second marker at a right anatomy of the patient; determining from oneor more images captured by the imaging device a difference between aproximity of the first marker to the imaging device and a proximity ofthe second marker to the imaging device as an anatomical alignment ofthe patient.

The imaging device can include an RGB sensor and the first and secondmarkers can include colored flags. The left and right anatomies can bethe patient's left and right shoulders and the anatomical alignment caninclude a shoulder balance of the patient. The left and right anatomiescan be the patient's left and right hips and the anatomical alignmentcan include a hip balance of the patient. The method can includedisplaying first and second distances represented by the proximities ofthe first and second markers on an electronic display. The firstlocation can include a vertebra of the patient.

In some embodiments, a method for anatomical alignment includes securinga mechanical frame to a patient at the left and right feet of thepatient, the mechanical frame establishing a simulated ground plane;projecting a plumb line from a pointing device mounted to the frame, theplumb line extending perpendicular to the simulated ground plane; andadjusting an anatomy of the patient to the plumb line to correct ananatomical misalignment of the patient.

The method can include using the frame to lock movement of the patient'sankle joints. Adjusting the anatomy of the patient can include bringingthe patient's cervico-thoracic junction (CTJ) to the plumb line tobalance the patient's shoulders. Adjusting the anatomy of the patientcan include bringing the patient's lumbosacral joint L5-S1 to the plumbline to balance the patient's pelvis.

In some embodiments, a system for anatomical alignment includes amechanical frame configured to be secured to a patient at the left andright feet of the patient; and a pointing device mounted to the frameand configured to project a plumb line therefrom, the plumb lineextending perpendicular to a simulated ground plane established by themechanical frame.

The frame can include attachment features for securing the frame to thepatient. The frame can lock movement of the patient's ankle joints.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a misaligned human spine;

FIG. 1B illustrates a “correct” anatomical alignment along with variousanatomical misalignments with which a patient may be afflicted;

FIG. 1C illustrates an exemplary comparison between a “correct”anatomical alignment and an anatomical misalignment;

FIG. 2A is a perspective view of a patient instrumented with a systemfor anatomical alignment;

FIG. 2B is a top view of the patient and system of FIG. 2A;

FIG. 3A is a perspective view of a patient instrumented with a systemfor anatomical alignment;

FIG. 3B is a top view of the patient and system of FIG. 3A;

FIG. 4A is a perspective view of a patient instrumented with a systemfor anatomical alignment;

FIG. 4B is a top view of the patient and system of FIG. 4A;

FIG. 5A is a perspective view of a patient instrumented with a systemfor anatomical alignment;

FIG. 5B is a top view of the patient and system of FIG. 5A;

FIG. 6A is a perspective view of a system for anatomical alignmentinstrumented with a patient's shoulders;

FIG. 6B is a top view of the patient and system of FIG. 6A beforeshoulder leveling;

FIG. 6C is a top view of the patient and system of FIG. 6A aftershoulder leveling;

FIG. 6D is a top view of a display of the system of FIG. 6A;

FIG. 6E is a top view of the system of FIG. 6A instrumented with apatient's hips;

FIG. 6F is a top view of a patient and a variation of the system of FIG.6A before shoulder leveling;

FIG. 6G is a top view of a patient and a variation of the system of FIG.6A after shoulder leveling;

FIG. 7A is a perspective view of a patient instrumented with a systemfor anatomical alignment;

FIG. 7B is a top view of the patient and system of FIG. 7A; and

FIG. 8 is a schematic diagram of a computer system that can be used withthe systems above.

DETAILED DESCRIPTION

Systems and methods for anatomical alignment are disclosed herein. Insome embodiments, the systems and methods can provide accurate andcontinuous intraoperative validation of anatomical alignment, e.g., ofthe spine, hips, pelvis, and/or shoulders. An exemplary system caninclude a sensor and marker arrangement for measuring coronal imbalance.Another exemplary system can include a sensor and marker arrangement forshoulder or pelvic leveling. Yet another exemplary system can include amechanical frame for establishing a simulated ground plane andprojecting a plumb line from the simulated ground plane.

Systems and methods herein can provide continuous intraoperativevalidation of anatomical alignment. Such systems and methods can beactively used without interfering with a surgical procedure. This canallow anatomical alignment to be assessed intraoperatively, whileactions can still be taken to correct suboptimal alignment. Systems andmethods herein can reduce wound exposure time, reduce the number ofsteps in the procedure, reduce setup errors, reduce frustration, improvespeed, and provide enhanced ease of use.

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments.

FIG. 1A is a schematic diagram of a misaligned human spine. Theillustrated spine has a scoliotic curvature defined by an apicalvertebral translation (AVT). In addition, the illustrated spine has acoronal imbalance, as defined by an offset in the coronal plane betweena vertical plumb line extending from the center of the C7 vertebral bodyand the central sacral vertical line (CSVL) of the patient. The offsetcan be referred to as the C7-S1 coronal vertical axis (CVA). In general,it is preferred that the offset be brought as close to zero as possible,with an offset of 2 cm or less typically being considered normal. Whilethe coronal imbalance is measured between C7 and CSVL in the illustratedexample, it will be appreciated that the imbalance can exist and/or canbe measured from other vertebrae, e.g., other cervical vertebrae,thoracic vertebrae such as T1, or lumbar vertebrae.

FIG. 1B illustrates a “correct” anatomical alignment along with variousanatomical misalignments with which a patient may be afflicted. Examplesinclude, from left to right, high shoulder, high hip, head tilt, andsevere scoliosis. FIG. 1C illustrates another exemplary comparisonbetween a “correct” or “balanced” anatomical alignment (shown at rightwith the patient's shoulders, hips, and knees being level) and ananatomical misalignment (shown at left with a dropped shoulder, tiltedpelvis, rotated knee, and dropped arch).

Systems and methods herein can measure these and other anatomicalalignments, optionally continuously and/or in real time during a surgeryto facilitate correction of the alignment.

FIGS. 2A-2B illustrate an exemplary system 200 for anatomical alignmentthat can be used, for example, to measure coronal distance. As shown,the system 200 can include a pointing device 202 and a marker 204.

The pointing device 202 can be configured to project a visual indicatoronto the marker 204. The pointing device 202 can include any of avariety of features for projecting the visual indicator, such as alaser, LED pointer, and the like. The pointing device 202 can projectthe visual indicator in a straight line, e.g., in a line that does notcurve in the coronal or sagittal planes.

The pointing device 202 can include an attachment element 206 forattaching the pointing device to the patient. The attachment element 206can be configured to attach the pointing device 202 to an exterior ofthe patient, for example using an adhesive, clamp, strap, suture, etc.,or can be configured to attach the pointing device to internal anatomyof the patient, for example using a bone pin, bone screw, suture, clamp,etc. The attachment element 206 can be adjustable in one or more degreesof freedom to facilitate alignment of the pointing device 202. In someembodiments, the attachment element 206 allows for six degree-of-freedomadjustment of the pointing device 202 relative to the patient. Theattachment element 206 can be lockable in a fixed position such that thepointing device 202 cannot translate or rotate relative to the patient.In some embodiments, multiple bone pins can be used to secure thepointing device 202 to the patient to prevent rotation of the pointingdevice relative to the patient. The attachment element 206 can supportthe pointing device 202 in an elevated position to give the pointingdevice a clear line of sight over the patient's anatomy.

The pointing device 202 can include an alignment guide 208 to assist theuser in aligning the pointing device with the patient. For example, thepointing device 208 can include a bubble level, an accelerometer,gyroscope, or other sensor, or a beacon or marker for use with asurgical navigation system. The alignment guide 208 can allow forprecise positioning of the pointing device 202 with respect to thepatient, e.g., to align the projected visual indicator with ananatomical axis of the patient such as the CSVL. The alignment guide 208can be omitted and the pointing device 202 can be aligned visually.Alignment of the pointing device 202 can be confirmed using imagingtechniques such as fluoroscopy, CT, or MRI.

The marker 204 can include a measurement scale 210. The measurementscale 210 can include indicia or gradations arranged along a measurementaxis MA, such as a plurality of numbered lines as shown, to allow visualassessment of distances along the measurement axis. In the illustratedembodiment, the marker 204 includes a single measurement axis MA,aligned for measuring an offset in the coronal plane of the patient. Inother embodiments, the measurement axis MA can be aligned for measuringan offset in the sagittal or transverse plane of the patient. In stillfurther embodiments, the measurement scale 210 can include multiplemeasurement axes, e.g., a first measurement axis for measuring coronalbalance and a second measurement axis for measuring sagittal balance. Insome embodiments, the measurement scale 210 can include atwo-dimensional grid onto which the visual indicator of the pointingdevice 202 is projected.

The marker 204 can include an attachment element 212 for attaching themarker to the patient. The attachment element 212 can be configured toattach the marker to an exterior of the patient, for example using anadhesive, clamp, strap, suture, etc., or can be configured to attach themarker to internal anatomy of the patient, for example using a bone pin,bone screw, suture, clamp, etc. The attachment element 212 can beadjustable in one or more degrees of freedom to facilitate alignment ofthe marker 204. In some embodiments, the attachment element 212 allowsfor six degree-of-freedom adjustment of the marker 204 relative to thepatient. The attachment element 212 can be lockable in a fixed positionsuch that the marker 204 cannot translate or rotate relative to thepatient. In some embodiments, multiple bone pins can be used to securethe marker 204 to the patient to prevent rotation of the marker relativeto the patient. The attachment element 212 can support the marker 204 inan elevated position to give the marker a clear line of sight over thepatient's anatomy.

The marker 204 can include an alignment guide 214 to assist the user inaligning the marker with the patient. For example, the marker 204 caninclude a bubble level, an accelerometer, gyroscope, or other sensor, ora beacon or marker for use with a surgical navigation system. Thealignment guide 214 can allow for precise positioning of the marker 204with respect to the patient, e.g., to align the measurement axis MA suchthat it is perpendicular to the patient's sagittal plane. The alignmentguide 214 can include features for projecting a visual indicator, suchas a laser, LED pointer, and the like. As shown, when beam-typeindicators are used for the marker 204 and the pointing device 202,proper alignment of the marker and pointing device can be confirmed bycomparing the beams to one another and to the sagittal plane of thepatient to confirm that the beams and the sagittal plane are eachparallel to one another. The alignment guide 214 can be omitted and themarker 204 can be aligned visually. Alignment of the marker 204 can beconfirmed using imaging techniques such as fluoroscopy, CT, or MRI.

In use, the pointing device 202 and the marker 204 can be positionedopposite to one another along the patient and can be attached to thepatient. In the illustrated embodiment, the pointing device 202 isattached to the patient's S1 vertebra and the marker 204 is attached tothe patient's T1 vertebra, though it will be appreciated that thepointing device and marker can be attached at any of a variety oflocations on the patient, depending on the measurement of interest.

The alignment guides 208, 214 and attachment elements 206, 212 of thepointing device 202 and the marker 204 can be checked and adjusted asneeded to confirm proper alignment. For example, the pointing device 202can be aligned such that the projected visual indicator is parallel toand in the same sagittal plane as the patient's CSVL and such that theprojected visual indicator lands on the measurement scale 210. Themarker 204 can be aligned such that the measurement axis MA extendsperpendicular to a vertical plumb line extending from the center of T1.Accordingly, the surgeon can quickly assess the patient's T1-S1 CVA bysimply observing the location along the measurement scale 210 at whichthe projected visual indicator lands. The pointing device 202 and themarker 204 can remain attached to the patient as long as desired by thesurgeon, and the visual indicator left “on,” such that the system 200can continuously validate coronal balance of the patient's spine. Thesystem 200 can thus provide a continuous, real-time indication to thesurgeon of the patient's coronal balance.

It will be appreciated that the positioning of the pointing device 202and the marker 204 can be reversed. In other words, the pointing device202 can be attached at a more-superior location on the patient and themarker 204 can be attached at a more-inferior location on the patient.In some embodiments, the pointing device 202 and the marker 204 can beidentical components, and thus can be used in either roleinterchangeably.

In some embodiments, a method for assessing anatomical alignmentincludes attaching a pointing device to a first location on a patient,attaching a marker to a second location on a patient, and projecting avisual indicator from the pointing device onto a measurement scale ofthe marker to provide a direct visual indication of an anatomicalmeasurement of the patient. The first position can be the pelvis or aninferior vertebra, the second position can be a superior vertebra, andthe anatomical measurement can be a CVA of the patient.

FIGS. 3A-3B illustrate an exemplary system 300 for anatomical alignmentthat can be used, for example, to measure coronal distance. As shown,the system 300 can include first and second range finder systems 316A,316B. Each range finder system 316A, 316B can include a transceivercomponent 320 and a target component 322 and can be configured tomeasure the range, or distance between the components, e.g., bymeasuring a time of flight from when an output signal is emitted fromthe transceiver to when the output signal is reflected off of the targetand received back at the transceiver. Exemplary range finders can useoptical sensors, pulsed laser sensors, acoustic sensors, or infraredsensors to measure time of flight. In the illustrated embodiment, thesystem 300 includes two range finders 316, though it will be appreciatedthat any number of range finders can be used, e.g., to provideredundancy or to measure additional anatomical dimensions. In someembodiments, a single transceiver 320 can be used to measure time offlight to multiple targets 322.

The first and second range finders 316A, 316B can each include a targetcomponent 322 mounted to the patient and a transceiver component 320mounted or positioned along a fixed reference axis, e.g., mounted to theedge of the operating table 324 as shown. In other embodiments, thetarget component 322 can be positioned along the reference axis and thetransceiver component 320 can be mounted to the patient. The firsttarget component 322A can be coupled to a first location on the patient,such as T1, and the second target component 322B can be coupled to asecond location on the patient, such as S1. In use, the respective timesof flight measured by the transceivers 320A, 320B of the first andsecond range finders 316A, 316B can be compared to determine a distancebetween the first and second target components 322A, 322B. For example,the range finders 316 can measure the relative distance between thetarget components 322 in the coronal plane which, in the example above,is commensurate with the T1-S1 CVA of the patient. In the illustratedembodiment, the targets 322 are attached to the patient's S1 and T1vertebrae, though it will be appreciated that the targets can beattached at any of a variety of locations on the patient, depending onthe measurement of interest. In some embodiments, the transceivers 320and the targets 322 can be identical components, and thus can be used ineither role interchangeably.

The system 300 can include an indicator for communicating the measureddistance to the surgeon. For example, the system 300 can include acontroller that drives an electronic display 326 to graphically displaythe relative distance to the surgeon. By way of further example, thesystem can emit audible, visual, and/or tactile feedback when therelative distance is within an acceptable range, e.g., when the measuredCVA is within a predetermined distance of zero, such as +/−2 cm, or whenthe relative distance is outside of an acceptable range. The feedbackcan be emitted by a light such as an LED, a speaker, a buzzer, avibrator, etc.

The transceiver and/or target components of the range finders 316 caninclude an attachment element 328 for attaching the component to thepatient or to a fixed reference point, as the case may be. Theattachment element 328 can be configured to attach the component to anexterior of the patient, for example using an adhesive, clamp, strap,suture, etc., or can be configured to attach the component to internalanatomy of the patient, for example using a bone pin, bone screw,suture, clamp, etc. The attachment element 328 can be adjustable in oneor more degrees of freedom to facilitate alignment of the range findercomponents. In some embodiments, the attachment element 328 allows forsix degree-of-freedom adjustment of the component relative to thepatient or reference point. The attachment element 328 can be lockablein a fixed position such that the component cannot translate or rotaterelative to the patient or reference point. In some embodiments,multiple bone pins can be used to secure the component to the patient toprevent rotation of the component relative to the patient. Theattachment element 328 can support the component in an elevated positionto give the component a clear line of sight over the patient's anatomy.

The transceiver and/or target components of the range finders 316 caninclude an alignment guide 330 to assist the user in aligning thecomponents with the patient, with the reference axis, and with eachother. For example, the components can include a bubble level, anaccelerometer, gyroscope, or other sensor, or a beacon or marker for usewith a surgical navigation system. The alignment guide 330 can allow forprecise positioning of the components with respect to the patient andthe reference axis, e.g., to align the incident path and reflected pathof the emitted signals such that they are perpendicular to the sagittalplane, plumb line, or CSVL of the patient and to the reference axis. Thealignment guide 330 can be omitted and the components can be alignedvisually. Alignment of the components can be confirmed using imagingtechniques such as fluoroscopy, CT, or MRI. In some embodiments, one orboth components of the range finders 316 can be configured to project avisual indicator onto the opposite component. The components can includeany of a variety of features for projecting the visual indicator, suchas a laser, LED pointer, and the like. The component can project thevisual indicator in a straight line, e.g., in a line that does not curvein the coronal or sagittal planes. The projected visual indicators canbe used to confirm alignment between the transceiver and target.

In use, the targets 322 can be attached to the patient and thetransceivers 320 can be attached along the reference axis, or viceversa. The alignment guides 330 and attachment elements 328 of the rangefinder components can be checked and adjusted as needed to confirmproper alignment. The times of flight measured by the range finders 316can be compared, e.g., using a processor, controller, computer system,etc., to determine a relative distance between the targets 322 andtherefore determine an anatomical measurement of the patient. Forexample, the range finders 316 can measure the relative distance betweenthe target components 322 in the coronal plane which, in the exampleabove, is commensurate with the T1-S1 CVA of the patient. The anatomicalmeasurement can be communicated to the surgeon such that the surgeon canquickly assess the measurement in real time and continuously throughoutthe surgery.

In some embodiments, a method for assessing anatomical alignment caninclude attaching a first range finder component at a first location ona patient, positioning a second range finder component at a referenceaxis, attaching a third range finder component at a second location onthe patient, positioning a fourth range finder component at thereference axis, measuring a first time of flight between the first andsecond components, measuring a second time of flight between the thirdand fourth components, and comparing the first and second times offlight to determine an anatomical measurement of the patient. The firstlocation can be the pelvis or an inferior vertebra, the second locationcan be a superior vertebra, and the anatomical measurement can be a CVAof the patient. The method can include communicating the determinedanatomical measurement to a user using at least one of a visualindicator, an audible indicator, a tactile indicator, and an electronicdisplay.

FIGS. 4A-4B illustrate an exemplary system 400 for anatomical alignmentthat can be used, for example, to measure coronal distance. As shown,the system 400 can incorporate features of the systems 200, 300described above. In particular, the system 400 can include a pointingdevice 402 and a range finder 416 having a transceiver component 420 anda target component 422. The pointing device 402 can be attached to thepatient as in the pointing device 202 in the system 200 above, and oneof the range finder components 422 can be attached to the patient as inthe marker 204 in the system 200 above. The other range finder component420 can be held by the user or attached to the patient at a locationoffset laterally from the first range finder component 422, asdetermined by the visual indicator projected from the pointing device402. In other words, the range finder target component 422 can beattached to T1, and the range finder transceiver component 420 can bepositioned opposite the target at a location where the projected visualindicator of the pointing device 402 is incident on the transceiver. Theopposite arrangement can also be used, i.e., in which the transceiver420 is attached to the patient and the target 422 is aligned with thepointing device 402. The range finder 416 can then measure the time offlight between the transceiver 420 and the target 422 and therebydetermine the relative distance between the two. In the illustratedembodiment, the relative distance between the transceiver 420 and thetarget 422 equates to the T1-S1 CVA of the patient. It will beappreciated that the illustrated attachment points are merely exemplaryand that the system 400 can be used to determine any of a variety ofanatomical measurements of the user. In the system 400, the range finder416 measures the target dimension directly, as opposed to comparingfirst and second times of flight as in the system 300 above. Thedetermined anatomical measurement can be communicated to the user asdescribed above, for example using an electronic display 426.

In some embodiments, a method for assessing anatomical alignment caninclude attaching a pointing device at a first location of a patient,attaching a first range finder component at a second location of thepatient, the second location being aligned in the coronal plane of thepatient with the first location, attaching a second range findercomponent at a third location of the patient, and measuring a time offlight between first and second range finder components to determine ananatomical measurement of the patient.

FIGS. 5A-5B illustrate an exemplary system 500 for anatomical alignmentthat can be used, for example, to measure coronal distance. Except asindicated below and as will be readily apparent to one having ordinaryskill in the art, the structure and operation of the system 500 issubstantially identical to that of the system 200 described above, andtherefore a detailed description is omitted here for the sake ofbrevity. The system 500 and the components thereof can include any ofthe features of the systems described above, including attachmentfeatures, alignment guides, and the like.

In the system 500, an imaging device 502 is used in place of thepointing device 202 of the system 200 and a marker 504 having apredetermined color, marking, pattern, etc. is used in place of themarker 204 of the system 200. The field of view of the imaging devicecan be aligned, calibrated, or registered to the CSVL or other referenceaxis of interest of the patient, such that a location of the marker 504relative to the reference axis can be determined from the capturedimage. For example, the imaging device 502 can be marked with aradiopaque line to denote the central axis of the image sensor, and theline can be aligned with the reference axis of the patient usingfluoroscopy. By way of further example, anatomical landmarks of thepatient, such as the median sacral crest or a spinous process of alumbar vertebra, can be identified within the captured image to locatethe reference axis. As yet another example, the imaging device 502 canbe aligned visually. A controller can execute an image processingroutine to identify the marker 504 within the captured image and tocalculate an offset between the marker and the reference axis, therebycalculating an anatomical measurement of the patient, e.g., a T1-S1 CVAas shown.

Any of a variety of known imaging devices 502 can be used, includingCCD, CMOS, or NMOS image sensors, photodiodes, optical sensors, videotracker sensors, video surface sensors, fiber optic sensors, laser scansensors, electromagnetic sensors, combinations of sensors describedherein, and so forth. In some embodiments, the imaging device 502 can bea RGB sensor, e.g., a commercially available RGB-D sensor. The marker504 can be colored red, green, or blue to facilitate recognition by theRGB sensor.

The determined anatomical measurement can be communicated to the user asdescribed above, for example using an electronic display 526 as shown.The electronic display can be integral with the image sensor 502 or partof a remote computer system. The system 500 can communicate the offsetto the user along with the direction of the offset, e.g., left or rightas shown.

FIGS. 6A-6G illustrate an exemplary system 600 for anatomical alignmentthat can be used, for example, for shoulder and/or pelvic leveling.

As shown in FIGS. 6A-6C, the system 600 can include left and right rangefinders 616A, 616B. The left range finder 616A can include a transceivercomponent 620A and a target component 622A, and the right range findercan include a transceiver component 620B and a target component 622B.The range finders 616 can include any of the features of the rangefinders described above, including attachment elements, alignmentguides, and so forth. In some embodiments, a single transceivercomponent 620 can measure times of flight to multiple target components622.

In use, the times of flight measured by the range finders 616A, 616B canbe compared, e.g., using a processor, controller, computer system, etc.to determine a relative distance between the targets 622A, 622B andtherefore determine an anatomical measurement of the patient. Theanatomical measurement can be communicated to the surgeon such that thesurgeon can quickly assess the measurement in real time and continuouslythroughout the surgery.

In the illustrated embodiment, the range finder transceivers 620A, 620Bare attached to the patient's S1 vertebra and the range finder targets622A, 622B are attached to the patient's left and right shoulders,respectively, for example to the superior angle of the left scapula andthe superior angle of the right scapula. The difference in time offlight measured by the left and right range finders 616A, 616B can thusindicate an amount of shoulder imbalance in the patient. As shown inFIG. 6B, a distance X represented by the time of flight measured by theleft range finder 616A differs from a distance Y represented by the timeof flight measured by the right range finder 616B when the patient'sshoulders are unbalanced. As shown in FIG. 6C, the distances Zrepresented by the times of flight measured by the left and right rangefinders 616A, 616B are equal or substantially equal when the patient'sshoulders are balanced or level. The distances measured by the left andright range finders 616A, 616B can be communicated to the surgeon, forexample using an electronic display 626 as shown in FIG. 6D. Thelocation on the display at which the measurement is shown can becoordinated with the location on the patient on which the range finderis mounted. For example, a measurement obtained from the left rangefinder 616A can be displayed on a left side of the display 626 and ameasurement obtained using the right range finder 616B can be displayedon a right side of the display. Thus, in the illustrated example, thesurgeon can readily observe from the display 626 that the left shoulderis 10 cm lower than the right shoulder.

The system 600 can be used to measure other anatomical alignments of thepatient, such as hip or pelvis balance as shown in FIG. 6E. As shown,the range finder targets 622A, 622B can be attached to the patient'ships, for example at the outer edge of the iliac crest. The system 600can be used as described above to convey to the surgeon the degree ofbalance or imbalance of the patient's pelvis.

While a range finder arrangement is shown and described above, it willbe appreciated that the system 600 can use other measurement technologyinstead or in addition. For example, as shown in FIGS. 6F-6G, the system600 can include an imaging device 602 of the type described above andleft and right markers 604A, 604B configured to be detected in imagescaptured by the imaging device. In some embodiments, the imaging device602 can be an RGB sensor and the markers 604A, 604B can have differentcolors, e.g., one blue and one green, to make them easilydistinguishable by the RGB sensor. In use, image data captured by theimage sensor 602 can be processed to determine the relative proximity ofthe left and right markers 604A, 604B to the imaging device. Forexample, the size of the markers 604A, 604B within the captured imagecan be determined to assess the proximity of the markers. As shown inFIG. 6F, the proximity X of the left marker 604A differs from theproximity Y of the right marker 604B when the patient's shoulders areunbalanced. As shown in FIG. 6G, the proximity Z of the left and rightmarkers 604A, 604B is equal or substantially equal when the patient'sshoulders are balanced or level. The system 600 shown in FIGS. 6F-6G canalso be used for pelvic leveling or for assessing other anatomicalalignment. Any of a variety of known imaging devices 602 can be used,including CCD, CMOS, or NMOS image sensors, photodiodes, opticalsensors, video tracker sensors, video surface sensors, fiber opticsensors, laser scan sensors, electromagnetic sensors, combinations ofsensors described herein, and so forth.

FIGS. 7A-7B illustrate an exemplary system 700 for anatomical alignmentthat can be used, for example, for shoulder and/or pelvic leveling,especially in patients with leg length discrepancy. As shown, the system700 can include a mechanical frame 732 for establishing a simulatedground plane with respect to the patient, for example when the patientis lying on the operating table. The frame 732 can include a pointingdevice 702, e.g., of the type described above, configured to project avisual indicator. The pointing device can include any of a variety offeatures for projecting the visual indicator, such as a laser, LEDpointer, and the like. The pointing device 702 can project the visualindicator in a straight line, e.g., in a line that does not curve in thecoronal or sagittal planes. In the illustrated embodiment, the pointingdevice 702 projects a light beam 734 that acts as a plumb line which isperpendicular to the simulated ground plane of the frame 732.Accordingly, the frame 732 can be attached to the patient and variousportions of the patient's anatomy can be compared to the plumb line 734to assess alignment. As shown in FIG. 7B, a patient with a leg lengthdiscrepancy can present with a pelvic side shift and a shoulder sideshift as compared to the plumb line 734. The surgeon can correct themisalignment, for example by bringing the patient's cervico-thoracicjunction (CTJ) to the plumb line 734 to balance the shoulders and/or bybringing the patient's lumbosacral joint L5-S1 to the plumb line 734 tobalance the pelvis.

The frame 732 can be secured to the patient at any of a variety oflocations. In the illustrated embodiment, the frame 732 is secured tothe patient's lower extremities with a foot plate 736 pressed firmlyagainst the patient's heels. The foot plate 736 can thus define asimulated ground plane that intersects with the left and right heels ofthe patient. The frame 732 can include straps or other attachmentfeatures 738 for securing the frame to the patient. The frame 732 can beconfigured to lock or restrict movement of one or more of the patient'sjoints. In the illustrated embodiment, the frame 732 locks out thepatient's ankle joints. In other embodiments, the frame 732 can lock outother joints of the patient instead or in addition, such as the kneejoints, hip joints, etc.

Any one or more of the systems described above can include a controller,data processor, or computer system, e.g., for processing sensor outputsor captured images, comparing measured ranges, calculating anatomicalalignments, displaying an anatomical measurement to a user, and soforth.

FIG. 8 illustrates an exemplary computer system 800 that can be usedwith any of the anatomical alignment systems described above. While anexemplary computer system 800 is depicted and described herein, it willbe appreciated that this is for sake of generality and convenience. Inother embodiments, the computer system 800 may differ in architectureand operation from that shown and described here. The computer system800 can be a tablet computer, mobile device, smart phone, laptopcomputer, desktop computer, cloud-based computer, server computer, andso forth. Software can execute on the computer system 800. The softwarecan execute on a local hardware component (e.g., a tablet computer,smart phone, laptop computer, or the like) or can execute remotely(e.g., on a server or cloud-connected computing device in communicationscoupling with the computer system 800). The computer system 800 can bephysically or communicatively connected, e.g., in real-time, with othersoftware or hardware systems, including Software as a Medical Device(SaMD), pre-operative planning software, a Picture Archiving andCommunication System (PACS), an Electronic Medical Record (EMR) system,an Electronic Health Record (EHR) system, and/or an electronicPatient-Reported Outcome (ePRO) system. The computer system 800 can beconnected to such other systems for data transfer, data analytics,machine learning, and/or real-time prescriptive clinical decision makingfor surgical intervention and correction.

The illustrated computer system 800 includes a processor 840 whichcontrols the operation of the computer system, for example by executingembedded software, operating systems, device drivers, applicationprograms, and so forth. The processor 840 can include any type ofmicroprocessor or central processing unit (CPU), including programmablegeneral-purpose or special-purpose processors. As used herein, the termprocessor can refer to microprocessors, microcontrollers, ASICs, FPGAs,PICs, processors that read and interpret program instructions frominternal or external memory or registers, and the like. The computersystem 800 also includes a memory 842, which provides temporary orpermanent storage for code to be executed by the processor 840 or fordata that is processed by the processor. The memory 842 can includeread-only memory (ROM), flash memory, one or more varieties of randomaccess memory (RAM), and/or a combination of memory technologies. Thevarious components of the computer system 800 can be interconnected viaany one or more separate traces, physical busses, communication lines,etc.

The computer system 800 can also include a communication or networkinterface 844 and an I/O interface 846. The network interface 844 canenable the computer system 800 to communicate with remote devices (e.g.,other computer systems) over a network or communications bus (e.g., auniversal serial bus). The I/O interface 846 can facilitatecommunication between one or more input devices, one or more outputdevices, and the various other components of the computer system 800.Exemplary input or output devices include electronic displays, touchscreens, mechanical buttons, keyboards, pointing devices, and anatomicalalignment sensors or components (e.g., pointing devices, range finders,and imaging devices of the type described above). The computer system800 can also include a storage device 848, which can include anyconventional medium for storing data in a non-volatile and/ornon-transient manner. The storage device 848 can include one or morehard disk drives, flash drives, USB drives, optical drives, variousmedia disks or cards, and/or any combination thereof and can be directlyconnected to the other components of the computer system 800 or remotelyconnected thereto, such as through the communication interface 844. Theelements illustrated in FIG. 8 can be some or all of the elements of asingle physical machine. In addition, not all of the illustratedelements need to be located on or in the same physical machine.

The various functions performed by the computer system 800 can belogically described as being performed by one or more modules. It willbe appreciated that such modules can be implemented in hardware,software, or a combination thereof. It will further be appreciated that,when implemented in software, modules can be part of a single program orone or more separate programs, and can be implemented in a variety ofcontexts (e.g., as part of an embedded software package, an operatingsystem, a device driver, a standalone application, and/or combinationsthereof). In addition, software embodying one or more modules can bestored as an executable program on one or more non-transitorycomputer-readable storage mediums. Functions disclosed herein as beingperformed by a particular module can also be performed by any othermodule or combination of modules.

It should be noted that any ordering of method steps expressed orimplied in the description above or in the accompanying drawings is notto be construed as limiting the disclosed methods to performing thesteps in that order. Rather, the various steps of each of the methodsdisclosed herein can be performed in any of a variety of sequences. Inaddition, as the described methods are merely exemplary embodiments,various other methods that include additional steps or include fewersteps are also within the scope of the present disclosure.

While the systems and methods illustrated and described herein generallyinvolve assessing alignment of the spine, hips, or shoulders of a humanpatient, it will be appreciated that the systems and methods herein canbe used to assess various other anatomical alignments, distances, etc.,in human, animal, or non-living subjects. The systems and methodsdisclosed herein can be used in minimally-invasive surgery and/or opensurgery.

The systems disclosed herein and the various component parts thereof canbe constructed from any of a variety of known materials. Exemplarymaterials include those which are suitable for use in surgicalapplications, including metals such as stainless steel, titanium, oralloys thereof, polymers such as PEEK, ceramics, carbon fiber, and soforth. The various components of the devices disclosed herein can berigid or flexible. One or more components or portions of the device canbe formed from a radiopaque material to facilitate visualization underfluoroscopy and other imaging techniques, or from a radiolucent materialso as not to interfere with visualization of other structures. Exemplaryradiolucent materials include carbon fiber and high-strength polymers.

Although specific embodiments are described above, it should beunderstood that numerous changes may be made within the spirit and scopeof the concepts described.

The invention claimed is:
 1. A method for assessing anatomicalalignment, comprising: attaching, during a surgical procedure, a firstrange finder component at a first location on a patient; attaching,during the surgical procedure, a second range finder component at a leftanatomy of the patient with respect to a sagittal plane of the patient;attaching, during the surgical procedure, a third range finder componentat a right anatomy of the patient with respect to the sagittal plane ofthe patient; measuring, using a processor, a first time of flight of afirst signal between the first and second components; measuring, using aprocessor, a second time of flight of a second signal between the firstand third components; and comparing, using a processor, the first andsecond times of flight to determine an anatomical alignment of the leftand right anatomies of the patient, wherein the first location is medialto least one of the second and third range finder components such thatthe first location is closer to a midline of the patient than both ofthe second and third range finder components.
 2. The method of claim 1,wherein the left and right anatomies are the patient's left and rightshoulders and wherein the anatomical alignment comprises a shoulderbalance of the patient.
 3. The method of claim 1, wherein the left andright anatomies are the patient's left and right hips and wherein theanatomical alignment comprises a hip balance of the patient.
 4. Themethod of claim 1, wherein the first component comprises a lefttransceiver aimed towards the second component and a right transceiveraimed towards the third component.
 5. The method of claim 1, furthercomprising displaying first and second distances represented by thefirst and second times of flight on an electronic display.
 6. The methodof claim 1, wherein the first location comprises a vertebra of thepatient.
 7. The method of claim 1, wherein the sagittal plane of thepatient aligns with the patient's central sacral vertical line.
 8. Themethod of claim 1, wherein the first location is centered about thesagittal plane.